This part is intended to provide background or context for embodiments of the invention stated in the claims. The description in this part is not considered as the conventional technology although the description is included in this part.
A blind area of a vehicle exists due to the structure of the vehicle. A driver sits in a driver's seat can not see target objects in the blind area. In our daily life, traffic accidents often happen due to the fact that the target object in the blind area can not be seen by the driver. In order to avoid or reduce traffic accidents due to the blind area of the vehicle, the driver is required to grasp situations in the blind area.
A technique has been proposed in which a shooting device is arranged at the rear of the vehicle, a scene in the blind area is shot by the shooting device and the shot image is detected to determine the target object in the blind area. Specifically, in the detecting process, by using an appearance feature of the target object, such as symmetry of the vehicle, shadows underneath the vehicle and a vertical edge of the vehicle, a possible candidate area of the target object is taken from the shot image, and then the target object is identified by using a knowledge-based method (such as template matching) or a classifier-based identifying method. However, there are various kinds of target objects, such as an automobile, a motorcycle and a bicycle, and even the same kind of target objects may have different shapes, for example, there is a difference in appearance between a large car and a sedan car. Therefore, it is difficult to take the possible candidate area of the target object from the shot image by using the appearance feature of the target object or to train a universal classifier applicable to various target objects for detecting the target object in the possible candidate area.